The sex determining region Y gene (SRY) is a critical factor responsible for the activation of Mullerian Inhibiting Substance (MIS), which initiates the regression of the Mullerian duct structures, the analgen of the uterus, fallopian tubes, and vagina. The specific regions of the MIS promoter acted upon by SRY to enhance expression are unknown, and experiments have suggested that SRY does not act alone. Recently the non-Y located genes SRY-related gene 9 (SOX 9) and the dosage sensitive sex reversal-adrenal hypoplasia congenital (DSS -AHC) critical region on the X chromosome, gene 1 (DAX 1) have been implicated in causing some forms of sex reversal. SRY is hypothesized to require an interaction with candidate factors such as SOX 9 or DAX 1 or novel factors, to activate MIS transcription. MIS promoter deletion experiments will be undertaken to define the specific regions under SRY's influence, and the yeast two hybrid screening method will be applied to test candidate factors for SRY interaction as well as to search for novel SRY interacting factors. Understanding the mechanisms by which SRY and other molecules mediates these pathways is of crucial importance to understanding sexual dimorphism.